<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        h3 {
            margin: 100px auto;
            width: 80px;
            height: 39px;

        }

        h3::before {
            display: inline-block;
            vertical-align: middle;
            content: '';
            width: 39px;
            height: 39px;
            background: url(icons/i2.png) no-repeat;
            background-size: 39px 39px;
        }
    </style>
</head>

<body>
    <h3>你好</h3>
</body>

</html>